The authors would like to express their gratitude to René Fehlmann for providing the PV inversion routine and support with an early version of the simulation setup and to Daniel Lüthi for expert help with the EM model. The neat deduction leading to Eq. (16) was pointed out to us by one of the reviewers. We thank ECMWF and MeteoSwiss for providing access to the meteorological data. This study was conducted in part with funding from the NCCR Climate program of the Swiss National Science Foundation.
Ambaum, M., , and W. Verkley, 1995: Orography in a contour dynamics model of large-scale atmospheric flow. J. Atmos. Sci., 52 , 2643–2662.
Blackmon, M. L., , J. E. Geisler, , and E. J. Pitcher, 1983: A general circulation model study of January climate anomaly patterns associated with interannual variation of equatorial Pacific sea surface temperature. J. Atmos. Sci., 40 , 1410–1425.
Branstator, G., 1985a: Analysis of general circulation model sea surface temperature anomaly simulations using a linear-model. Part I: Forced solutions. J. Atmos. Sci., 42 , 2225–2241.
Branstator, G., 1985b: Analysis of general-circulation model sea-surface temperature anomaly simulations using a linear-model. Part II: Eigenanalysis. J. Atmos. Sci., 42 , 2242–2254.
Branstator, G., 2002: Circumglobal teleconnections, the jet stream waveguide, and the North Atlantic Oscillation. J. Climate, 15 , 1893–1910.
Fehlmann, R., , and H. C. Davies, 1999: Role of salient PV-elements in an event of frontal-wave cyclogenesis. Quart. J. Roy. Meteor. Soc., 125 , 1801–1824.
Majewski, D., 1991: The Europa-Modell of the Deutscher Wetterdienst. Numerical Methods in Atmospheric Models, ECMWF Seminar Proceedings, Vol. 2, European Centre for Medium–Range Weather Forecasts, 147–191.
Massacand, A. C., , and H. C. Davies, 2001: Interannual variability of the extratropical Northern Hemisphere and the potential vorticity wave guide. Atmos. Sci. Lett.,2, doi:10.1006/asle.2001. 0027.
Nakamura, M., , and A. R. Plumb, 1994: The effects of flow asymmetry on the direction of Rossby wave breaking. J. Atmos. Sci., 51 , 2031–2045.
Palmén, E., , and C. N. Newton, 1948: A study of the mean wind and temperature distribution in the vicinity of the polar front in winter. J. Meteor., 5 , 220–226.
Polvani, L. M., , and R. Plumb, 1992: Rossby wave breaking, microbreaking, filamentation, and secondary vortex formation: The dynamics of a perturbed vortex. J. Atmos. Sci., 49 , 462–476.
Pomroy, H. R., , and A. J. Thorpe, 2000: The evolution and dynamical role of reduced upper-tropospheric potential vorticity in intensive observing period one of FASTEX. Mon. Wea. Rev., 128 , 1817–1834.
Pratt, L. J., , J. Earles, , P. Cornillon, , and J. F. Cayula, 1991: The non-linear behaviour of varicose disturbances in a simple model of the Gulf Stream. Deep-Sea Res., 38 , (Suppl. 1),. S591–S622.
Reed, R. J., , and E. F. Danielsen, 1960: Fronts in the vicinity of the tropopause. Arch. Meteor. Geophys. Bioklimatol., 11A , 1–17.
Schwierz, C., , and H. C. Davies, 2003: Evolution of a synoptic-scale vortex advecting toward a high mountain. Tellus, 55A , 158–172.
Simmons, A. J., , J. M. Wallace, , and G. W. Branstator, 1983: Barotropic wave propagation and instability, and atmospheric teleconnection patterns. J. Atmos. Sci., 40 , 1363–1392.
Sun, D. Z., , and R. S. Lindzen, 1994: A PV view of the zonal mean distribution of temperature and wind in the extratropical troposphere. J. Atmos. Sci., 51 , 757–772.